# Why Special Relativity is wrong and the speed of light is NOT the same for all observers **URL:** \ **Category:** In My Humble Opinion\ **Created:** [February 19, 2014, 4:31am UTC](https://boards.straightdope.com/t/why-special-relativity-is-wrong-and-the-speed-of-light-is-not-the-same-for-all-observers/681683 "2014-02-19T04:31:17Z")\ **Posts on this page:** 1\ **Showing post:** 186
**Author:** ![Ronald\_Raygun](https://avatars.discourse-cdn.com/v4/letter/r/c67d28/32.png) [@Ronald\_Raygun](https://boards.straightdope.com/u/Ronald_Raygun)\ **Post date:** [February 27, 2014, 11:47pm UTC](https://boards.straightdope.com/t/why-special-relativity-is-wrong-and-the-speed-of-light-is-not-the-same-for-all-observers/681683/186 "2014-02-27T23:47:48Z")
> [@mythoughts](#): > > The problem is that you can’t simultaneously close the doors since it only looks to be simultaneous to you. Let’s not dance around what this paradox is. This is the well-known ladder paradox (or barn paradox), and its resolution is precisely the fact that simultaneity is relative. I close the doors simultaneously _in my reference frame_. Yes, in a manner of speaking, this “looks to be simultaneous to [me]”, but this isn’t a problem. It looks simultaneous in one reference frame, and not simultaneous in a different reference frame. > [@mythoughts](#): > > But you can’t close them simultaneously, also it only works for a vanishingly small instant of time from the barns view. Precisely, because the plank leave the room again though a shut door. > It destroys the door No shit. At any non-zero speed, the plank can only remain in the barn for a finite amount of time. As this speed increases, the time decreases. What’s your point? > [@](#): > > However if the plank doesn’t exit but orbits around, now your argument fails. > > Or if you like, take a hexagon disk which will not quite fit into a cylinder and spin it up, now it can fit according to the stationary cylinder, but it has become an even worse fit form the disks perspective, you put it on and the hexagon fits into the cylinder nicely while it is unable to be put on. That is a paradox. > > Do you see how easy it is to find the flaws in the first example and how hard it in in the other? > > note:Hexagon to make the length contraction obvious. > > All of the arguments for SR like this are from the the one angle SR does sound plausible. > > The hexagon can’t be smaller and larger than the cylinder at the same time and once simultaneity issue problem is removed you cannot longer solve it. > > You can’t address MY thought experiment, you have to refer to a different one that can be solved. > > But thanks for at least ALMOST analysing my experiment. > Strange that it isn’t so obviously solved? OK. This is a different – but also well-known – paradox, the Ehrenfest paradox. I’m going to change your hexagonal disk back to a circular one, since by your own admission its peculiar geometry is to make visualization easier. The radius of your disk doesn’t shrink, because any point along the circumference moves orthogonally to the radial vector. Since the radius doesn’t shrink, your disk can’t fit into a cylinder of smaller radius. Yes, the circumference gets smaller by a factor of gamma. Since the circumference is no longer 2πR, we conclude that the disk is not in Euclidean space. Acceleration must warp spacetime. > [@mythoughts](#): > > And strange that the version you showed me can be understood without mathematics or knowing precisely how short the plank should be. > > I should insist that you prove yours with numbers I can’t check just for symmetry 🙂 This comment reveals that you don’t really understand what doing the math actually entails, and makes me suspect that you don’t trust mathematics because you refuse to put in the work to understand mathematics. You don’t need to assign a precise length to the plank – just call it L in the rest frame. The reasons I harp on you to do the mathematics is the following: – In a sense, the burden of proof is on you to explain why the paradox fails. Special relativity is a mathematical theory built upon a few axioms about the nature of the physical world. Any contradiction must be mathematical, and once you point out what that contradiction is, you should be able to trace it back to which axioms are in conflict, and thus which we need to get rid of or alter. – To expand on the previous point, no one said math is easy. It takes a lot of time, something that few people have. Since you are the one who wants to overturn relativity, please do so using mathematics or experimentation. Why am I limiting you to those? Because your paradox leads to contradiction due to common sense. Common sense is often wrong, particularly in physical regimes (such as relativistic or quantum ones) where our brains didn’t evolve, and so we must rely on experimentation and mathematics to navigate these domains. – Everyone is harping on you to do the math because when you do the math, you understand the problem and the paradox. This is why math textbooks are filled with proofs that are “exercises left for the reader”. You understand physical theories best when you solve problems with them. Similarly, you can’t understand how to paint by simply watching someone paint – you have to get your hands dirty and play around. Arguing by thought experiment is fine, but it only enables you to pose questions (which are frequently ill-proposed because your assumptions aren’t explicit). It does not equip you with the machinery to answer those questions. > [@](#): > > Not that I can’t add, subtract, multiply, divide and square, but I can’t read most most equations to save myself. So? If I showed up at an academic conference on Islam with a dissertation on a new and radical interpretation of the Koran, but I don’t understand a lick of Arabic, who would take me seriously? > [@](#): > > Oh, I also don’t trust math because it is very easy to do something with math and without realizing it you have done something that is mathematically sensible but not physically sensible. I don’t trust thought experiments because it is very easy to do something with language and without realizing it you have done something that is grammatically and semantically sensible but not physically sensible. I can do the same thing. > [@](#): > > Anyway can you really grasp the meaning of the find structure constant? > > It’s not even that I don’t think it has a meaning, but it is so abstract it is hard to reconnect it to reality. > > I think I may be vaguely understanding ‘alpha’, but I will admit it’s only a vague sense. > > And that seems to be a common opinion regarding 7.29735257… I fail to see what this has to do with anything. > [@](#): > > Which of my experiments are significantly effected by non-simultaneity? > > The people in the opposite cabins? Because non-simultaneity can only be small over a potentially small distance and at any rate is is unable to account for an ever increasingly larger discrepancy such as time not passing mutually for the opposite cabin. > > There are thought experiments that SR can easily explain. > > I am not making those arguments, so why not argue mine not others. > > Come on. A few things about this paradox > [@](#): > > If you look to the other side of the experiment you see a pretty girl in the cabin opposite (180 deg away) , and she is moving even faster relative to you than the earth, even though you can see her constantly she is moving extremely rapidly in the opposite direction. How is she moving relative to me if we always remain the same distance from each other? > [@](#): > > And she thinks the same should be happening to you! Even if we were moving past each other, why is this a problem? > [@](#): > > This contains no notable acceleration or deceleration to meet someone in another frame, just walk around the train. Really? _Really?_ Getting up from a stationary position and moving is not notable acceleration? > [@](#): > > If curving though space a bit drastically changed the rate you experienced time relative to a straight line journey then that would be news to everyone. But it does! If you curve through space, you’re in an accelerated reference frame! > [@](#): > > Because non-simultaneity can only be small over a potentially small distance… I’m not sure what you’re getting at here. I have a feeling you’re confused about how infinitesimal quantities can be related, but it seems like the crux of your complaints against special relativity can be encapsulated in this quote of yours: > [@](#): > > Indeed if this were so then significant degrees of time dilation (or acceleration actually!) could be achieved on earth easily by moving an object in a way that would make it consistent with orbiting a very distant point at near light speed. Are you referring obliquely to Selleri’s argument against special relativity? I’m not sure, but you’ve also made mention of walking around turntables and of trains on circular tracks, so I’d advise you to do some reading on the Sagnac effect, as well as on how different synchronization conventions cause Selleri’s paradox to disappear in the limit of an infinite radius (i.e., linear motion). --- _[View the full topic](https://boards.straightdope.com/t/why-special-relativity-is-wrong-and-the-speed-of-light-is-not-the-same-for-all-observers/681683)._